print('欢迎使用成绩分析器，请按照提示输入你的成绩。注意：此分析系统仅支持单科查询，分数必须在0~150之间，否则需重新输入。若存在疑问，可致电开发者：+86 13917818240,\nWelcome to use score analysis,please enter your score according to the instruction. Attention please: this system only support single subject analysis,the score should must between 0~150,or you have to enter again. If you have any concern, tele developer:+86 13917818240')
while True:
    s0 = int(input('请你选择语言，1为中文，2为英语（choose your language，1 means Chinese,2 means English）：'))
    if s0 in(1,2):
        break
    print('只能选择1或2（only choose 1 or 2）')

if s0==1:
    while True:
        s1 = int(input('请输入你去年的成绩：'))
        if 0 <= s1 <= 150:
            break
        print('成绩必须在 0~150 之间，请重新输入！')

    while True:
        s2 = int(input('请输入你今年的成绩：'))
        if 0 <= s2 <= 150:
            break
        print('成绩必须在 0~150 之间，请重新输入！')

    r = (s2 - s1) / s1 * 100

    if r == 0:
        print('你的成绩没有变化')
    elif r > 0:
        print(f'你成绩提升的百分点为 {r:.2f}%，成绩有进步')
    else:
        print(f'你成绩下降的百分点为 {-r:.2f}%，成绩退步了')
else:
    while True:
        s1 = int(input('Enter last year\'s score：'))
        if 0 <= s1 <= 150:
            break
        print('Score must be between 0 and 150, please re-enter！')

    while True:
        s2 = int(input('Enter this year\'s score:'))
        if 0 <= s2 <= 150:
            break
        print('Score must be between 0 and 150, please re-enter!')

    r = (s2 - s1) / s1 * 100

    if r == 0:
        print('Your score has not changed.')
    elif r > 0:
        print(f'Your score improved by {r:.2f}%')
    else:
        print(f'Your score decreased by {-r:.2f}%')